Correlation between times to SARS-CoV-2 symptom onset and secondary transmission undermines epidemic control efforts

Linton, N. M.; Akhmetzhanov, A. R.; Nishiura, H.

Severe acute respiratory coronavirus 2 (SARS-CoV-2) infections have been associated with substantial presymptomatic transmission, which occurs when the generation interval--the time between infection of an individual with a pathogen and transmission of the pathogen to another individual--is shorter than the incubation period--the time between infection and symptom onset. We collected a dataset of 257 SARS-CoV-2 transmission pairs in Japan and jointly estimated the mean generation interval (3.7-5.1 days) and mean incubation period (4.4-5.7 days) as well as measured their dependence (Kendall's tau of 0.4-0.6), taking into consideration demographic and epidemiological characteristics of the pairs. The positive correlation between the two parameters demonstrates that reliance on isolation of symptomatic COVID-19 cases as a focal point of control efforts is insufficient to address the challenges posed by SARS-CoV-2 transmission dynamics. Accounting for this dependence within SARS-CoV-2 epidemic models can also improve model estimates.